The present invention relates to a portable device powered by a replaceable battery to perform predetermined wireless communication with a certain communication peer.
A known electronic key system includes a portable device and a predetermined communication peer. The portable device is carried by an owner (user) of a vehicle, house, or the like. The communication peer is arranged in the vehicle, house, or the like. Wireless communication is performed between the portable device and communication peer to lock and unlock the vehicle, house, or the like. The portable device includes a replaceable battery and is powered by the battery when performing wireless communication with the communication peer.
Japanese Laid-Open Utility Model Publication No. 5-35980 discloses a waterproof portable device, which prevents the battery from being short-circuited by a liquid such as water. The portable device includes a case, which includes a battery compartment, and a battery lid, which covers the battery compartment. An O-ring is arranged between the case and the battery lid. The O-ring, which is compressed by fastening the battery lid to the case with a screw, prevents liquid from entering the battery compartment.